REACTION OF SODIUM PENTACYANONITROSYLFERRATE(2-) WITH ALIPHATIC THIOLATES - SYNTHESIS AND PROPERTIES OF THE [FE(CN)(5)N(O)SR](3-) PRODUCTS

Formation of the title complexes as red intermediate products (RP) of the reaction between pentacyanonitrosylferrate(2-) and aliphatic thiol ates was studied. The same compounds were also produced by another syn thetic method. The red products showed similar UV/vis and IR spectral properties and reactivity pathways, irrespective of the thiol nature. However, the RP lifetime was found to be strongly dependent on the thi ol structure, especially on the inductive effect of substituents. This finding enabled us to synthesize a novel, exceptionally stable RP wit h mercaptosuccinate as the thiolate ligand. The results showed that th e yield of the RP depends not only on pH and reactant concentrations b ut also strongly on the nature and the concentration of the cations. T he specific cation effect, reported earlier for the nitroprusside/cyst eine system, was found to initiate the reaction between nitroprusside and thiolates and to increase the RP stability for all the thiolates s tudied. The effect was interpreted in terms of ion-pair formation by b oth nitroprusside and the red product, The interaction of cations with the lone pairs of CN ligands was postulated to induce an electron shi ft within the complex that enables a nucleophilic attack of the thiola te on the NO ligand.